Fluid flow measurement is an important function in our daily lives. For example, a typical household in North America has at least two basic flow meters, one to measure the consumption of water and the other to measure the consumption of natural gas. Fluid flow measurement is also an important function for industry, for instance, where it is used to measure the amount of fluid transfer from one location to another. A typical utility company, such as Pacific Gas and Electric (PG&E™) needs to measure the amount of natural gas it transfers from storage facilities to distribution points, and then onward to consumers. Similarly, petroleum companies transport petroleum products from refineries to distribution points and onward to retailers. Furthermore, unknown to the typical end consumer, companies such as these make considerable use of fluid flow measurement in their manufacturing facilities. For instance, just in the major U.S. petrochemical processing centers of Torrance, Calif. and Houston, Tex., tens of thousands of fluid flow measuring devices are currently being employed.
Most existing flow meters require manual reading of the fluid flow. For example, PG&E personnel need to be sent periodically to each household or business to take natural gas meter readings. This is quite inefficient and costly. Another concern is that when fluid flow readings are taken manually, it may be difficult to humanly monitor the readings accurately or in a timely enough manner. For instance, there are frequent news reports of accidents where the leakage or breakage of natural gas or petroleum transport pipelines wastes money, causes safety hazards to nearby communities, and pollutes the environment. Accordingly, other approaches have long been sought.
Electrical flow meters are the primary alternative in use today. With suitable wiring these can permit remote fluid flow reading at some distance from the actual point of measurement. Unfortunately, there are many applications where the use of electrical flow meters is not practical. For example, the use of electricity can pose a fire hazard, particularly when the fluid itself or other materials around it are flammable. Also, many fluids react with metals such as copper and aluminum, which are the constituents of most electrical wire, or react with plastics, which are the desirable constituent of most electrical wire insulation. The monitoring distance for electrical flow meters may also be too short for many applications, because many of the monitoring devices require an adequate voltage to activate measurement components or because signal interference along long paths to and from those components may occur. Alternately, signal interference or electrical hazards caused by electrical wiring to electrical flow meters may be a concern for other nearby systems. For instance, in hospital operating rooms or sensitive laboratory environments.
In sum, improved systems for fluid flow measurement are needed. Such systems should preferably be non-electrical in principle and, without limitation, should work with both gas and liquid type fluids; work with wide ranges of chemically reactive fluids; work with fluids across a wide range of temperatures; permit reading at remote or more convenient locations; and permit entirely automated recording of readings.